Coaxial transfer switch

ABSTRACT

A rotary switch for coupling coaxial transmission lines which are connected to ports of the switch has a rotor for interconnecting any two adjacent ports by connecting the center conductors of the adjacent ports. The rotor is actuated by two electrical drives which drive the rotor in opposite directions, each to a predetermined position when the electrical drive is energized. Each electrical drive actuates a different set of micro-switches, one switch in each set controlling electrical power to the other electrical drive so that the drives are energized at different intervals and another switch in each set providing logic signals for turning transmitters on and off.

United States Patent [191 Vaughan et al.

1451 Feb. 4, 1975 COAXIAL TRANSFER SWITCH [76] Inventors: Thomas J. Vaughan, 201 Ray St.,

Manchester, NH. 03104; Richard A. Hickey, 622 Prescott St., Manchester, NH. 03103 221 Filed: Nov. 16,1972

21 Appl. No.: 307,193

[52] U.S. Cl 200/37 A, 200/l53, 333/7 [5 1] Int. Cl. H0lh 43/00 [58] Field of Search 200/153 P, 153 S, 37 A,

200/38 R, 35 R; 335/177, 183,73 ,333, 97 s; 318/35, 37, 134

[56] References Cited UNITED STATES PATENTS 2,556,869 6/1951 Charles 200/153 S Primary Examiner-Robert K. Schaefer Assistant ExaminerWilliam J. Smith Attorney, Agent, or Firm-Robert T. Dunn [57] ABSTRACT A rotary switch for coupling coaxial transmission lines which are connected to ports of the switch has arotor for interconnecting any two adjacent ports by connecting the center conductors of the adjacent ports. The rotor is actuated by two electrical drives which drive the rotor in opposite directions, each to a predetermined position when the electrical drive is energized. Each electrical drive actuates a different set of micro-switches, one switch in each set controlling electrical power to the other electrical drive so that the drives are energized at different intervals and another switch in each set providing logic signals for turning transmitters on and off.

10 Claims, 22 Drawing Figures PATENTEDFEB 419-75 3,864,536

SHEET 20F 5 a 1 I 30 a FIG. 5

WENTEU 41975 3,884,536

sum 3 OF 5 minnow 4W5 3.864.536

- SHEET QUF 5 no? 62b 75b 73b I E-4sb "72b I an \f l y a b 86 78b 79b 63b 8lb 82b 84b Fl 6. l0

fX SG o- A, T7? AC 5 loan" 0 Power 6 T 7 l Control{ 2 Logic 9lb F (5 66b G n lnreriock{ H o{ /66b a Fl 6. /2

55a r 95 A A A A A B 55b 5 B B B 5 locked Sw b closed Sw b open A Ocked A 'Ocked SW 0 closed 8w 0 closed SW 0 closed SW 0 open SW 0 open Sw b open SW D open Sw b closed F/6.//a FIG/lb FIG/l0 FIG/Id FIG/la wow 1 e A locked SW 0 closed 8w 0 open B locked B locked Sw b closed SW D closed Sw b oiosed Sw b open 8w b open SW 0 open SW 0 open SW 0 closed 'F/G. //f FIG. llg F/G. Ill; FI G. l/i FIG. ll]

PAIENTED FEB FAULT STANDBY DETECTOR TRANSMITTER TRANSMITTER ON- OFF SWITCH IIO T 3.864.536 SHEET 5 OF 5 CONTROL SWITCH CONTROLLER DEVICE I I I I I 92 l L AC 0 B F [IOI PRIMARY FAULT I TRANSMITTER DETECTOR TRANSMITTER TRANSMITTER ON-OFF LOGIC swITcH' CKTS Ioe TEA

FIG. /3

1 COAXIAL TRANSFER SWITCH This invention relates to rotary switches for use in transmission lines and more particularly for fast switching action between coaxial transmission lines to transfer radio frequency (rf) signals between transmission lines connected to alternate ports of the switch.

In radio frequency transmission systems it is sometimes required to transfer high power radio frequency signals between transmission lines. For this purpose, a four port transfer switch is provided with different transmission lines connected to the ports of the switch. A rotor inside the switch includes separate insulated electrical conductors which connect the center conductors of adjacent ports of the switch. For example, if the ports are numbered l to IV, at one position of the switch, the center conductors of ports I and II are connected and the center conductors of ports Ill and IV are connected and at another position of the switch, the center conductors of ports I and IV are connected while the center conductors of ports II and III are connected. In this configuration, the switch functions as a double pole, double throw switch. By leaving one port unconnected, the switch can also function as a single pole double throw switch.

It is sometimes required that a four port transfer switch whether functioning as a single pole double throw switch or as a double pole single throw switch, accomplish the switching action in an extremely short cycle time, typically around 180 milliseconds, and that the switching cycle be synchronized with the energization of a transmitter that feeds a transmission line connected to one of the ports of the switch. For example, in broadcast applications where high average power and fast switching time are required, it is sometimes desirable to switch off the transmitter and switch on a stand-by transmitter without any substantial loss or change in the broadcast signals. To accomplish this, switching time must be within a few hundred milliseconds, within which time the switch rotor must commence and complete its travel coming to a rest position without overshoot or misalignment. Furthermore, where the switching is electrically energized to operate automatically, it is required that accidental switching be impossible with loss of the energizing power to the switch. Furthermore, it is desirable to provide a manual override so that the switch can be actuated even when the switch electrical power is lost.

It is one object of the present invention to provide a relatively fast acting electrically energized drive for a multi port switch.

It is another object to provide the switch and switch drive for broadcast applications where relatively high average power and fast switching time are required.

It is another object to provide an electrically energized four port transfer switch for transferring high power rf signals between alternate ports of the switch.

It is another object to provide a mechanism for driving the rotor of a four port switch which mechanically locks the rotor at each position and produces electrical signals representative of the switch position.

It is another object to provide a mechanism for driving a four port coaxial transfer switch for high power broadcast application which mechanically locks the switch rotor at each position and produces electrical signals indicative of the switch rotor position.

It is a further object to provide such a switch drive mechanism by which a switching cycle is accomplished within a few hundred milliseconds.

It is a further object to provide such a switch drive and four port transfer switch for switching power from two rf transmitters between two loads, the produced electrical signals being used to turn the transmitters on and off.

In accordance with features ofa specific embodiment of the present invention described herein, a multi port coaxial transfer switch suitable for transferring relatively high average broadcast rf power between ports of the switch is provided with a drive mechanism for driving the switch rotor to accomplish switching in a few hundred milliseconds. The rotor is driven in one direction to a first switch position by one solenoid and is driven in the opposite direction to a second switch position by another solenoid. At each switch position, a mechanical lock is engaged to prevent overshoot and to secure the switch at the position. One position lock is unlocked by the rotation of one solenoid and the other is unlocked by the rotation of the other solenoid and so the switch is always mechanically locked except when a solenoid rotates sufficiently to unlock the switch as when the solenoid is electrically energized or mechanically manipulated, and each solenoid is energized from an electrical source via a switch actuated by rotation of the other solenoid. Both solenoids have spring returns and so tend to return when not energized to positions which initiates locking of the switch rotor. The switches which feed energizing power to the solenoids have logic and interlock switches ganged thereto which provide electrical signals for synchronizing the energization of, for example, primary and stand-by transmitters which transmit through the transfer switch.

The embodiment of the invention described herein with reference to the drawings represents the best known use of the invention.

In the drawings:

FIG. 1 is an external side view of the four port coaxial transfer switch with drive mechanism taken directly toward one of the ports;

FIG. 2 is a top view of the transfer switch and drive mechanism showing the manual control knobs and positions on the drive mechanism;

FIG. 3 is a top view of the transfer switch with the top thereof broken away to reveal the rotor configuration and knife switches whereby the rotor blades engage the center conductors at the ports of the switch;

FIG. 4 is a cross section view through ports II and IV of the switch parallel to the rotor axis showing the rotor knife blade connection to the center conductor of the port;

FIG. 5 is a cross section view through the ground bar at the center of the rotor parallel to the rotor axis;

FIGS. 6 and 7 are schematic drawings illustrating the port connections at the two positions A and B of the switch;

FIG. 8 is a front view of the drive mechanism with cover removed taken perpendicular to the rotor axis;

FIG. 9 is a view of the drive mechanism along the rotor axis taken as shown in FIG. 8;

FIG. 10 is a section view taken parallel to the axis of solenoid A showing details of the-mechanical locking mechanism and switch which controls energization of solenoid B;

FIGS. lla to 11] are diagrams showing the relative positions of the transfer switch, the solenoids, the switch rotor locks and the energization switches which control energization of the solenoids by which to gain ;ing power from two transmitters between typical loads.

A four port coaxial transfer switch for a broadcast application is illustrated in FIGS. 1 and 2. The switch 1 is equipped with a drive mechanism 2 enclosed by a housing 3 and having two manual control knobs 4 and 5 at the top of the housing. The switch 1 includes a body or housing 6 and four coaxial ports denoted I, II, III, and IV. Each of these ports such as port IV includes a center conductor 7 and outer conductor flange 8 for connection to a coaxial transmission line of the same size. For broadcast application, the size of these ports is usually "/a to 6 Vs inches in diameter. For the smaller size, the weight of the switch may be in the range of 10 pounds and for the larger size the weight may be in the range of 60 pounds.

Heretofore, the switching time for a switch of this size using conventional switch drive mechanisms has been on the order of l to 2 seconds and weight up to l20 pounds. The same transfer switch when equipped with the drive mechanism disclosed herein and shown in the figures is capable of switching within less than half a second and switching is accomplished automatically with positive drive to the switch rotor and a mechanical lock on the drive at each position of the switch rotor.

Within the transfer switch housing 6 is the transfer switch rotor 11. This rotor is rotatable about the axis 12 of the switch on an axel 13. The axel connects rigidly to the ground plate 14 of the rotor 11. This plate separates the two isolated conductive parts 15 and 16 of the rotor and is separated from them by dielectric strips 17 and 18, respectively. The axel, ground plate,

isolated conductive parts of the rotor and dielectric strips form a rigid assembly referred to herein as the rotor 11. The axel is carried at the bottom end by a bearing 19 axially located on the inside of the housing 6 of the switch. The other end of the axel 13 attaches to a spline 20 extending from a central idler gear in the transfer switch drive mechanism 2.

Within the drive mechanisms are two solenoids denoted herein solenoid A and solenoid B. Solenoid A drives the transfer switch to the B position of the switch and solenoid B drives to the A position of the transfer switch. These two positions A and B are indicated on the top of the drive mechanism housing 3 as shown in FIG. 2. Position A is indicated by pointer 4' on knob 4 that extends from the shaft of the solenoid A and position B is indicated by pointer 5' on knob 5 which extends from the shaft of solenoid B.

Within the housing 3, a drive from each solenoid to the transfer switch rotor 11 has a locking mechanism. When the switch is in the A position, the locking mechanism from solenoid A to the rotor locks and when in the B position, the locking mechanism from solenoid B to the rotor locks. Each of the solenoids has a springreturn which returns the solenoid to the position denoted operate on the top of the housing 3 and shown in FIG. 2 except when the drive from that solenoid to the transfer switch rotor is locked. When either solenoid is in the operate position, the drive from that solenoid closes an associated micro-switch which controls electrical energization of the other solenoid and also produces output logic or interlock signals. Thus, the position indicated by the knob as shown in FIG. 2, is that the transfer switch is in the A position, the drive from solenoid A to the rotor is locked and the energizing switch for solenoid A which is actuated by the drive from solenoid B, is closed. 5

The transfer switch rotor 11 is generally disc-shaped. The isolated conductive parts 15 and 16 make connec tion to the center conductors of adjacent parts of the switch. Extending from the ends of each of these conductive. partsare knife edges which engage widened slots at the ends of the center conductors of the four' ports of the switch. Blades 21 and 22 extend at right angles from the ends of conductive part 15 and blades 23 and 24 extend at right angles from the ends of conductive part 16. At the position of the transfer switch rotor shown in FIG. 3, which is the A position, knife edges 23 and 24 engage the center conductors of ports I and II, respectively, and the knife edges 21 and 22 engage the center conductors of ports III and IV, respectively. A sectional view through the rotor along the axis 12 of the switch taken as shown in FIG. 3 is illustrated in FIG. 4. This shows the engagement of the knife edge 22 extending from conductive part 18 of the rotor into a slot 26 in the center conductor 7 of port IV. This slot is preferably arched as is the knife edge 22 and the slot may be equipped with fingers or springs which are compressed as the knife edgemoves into the slot to insure substantial electrical contact between the knife edge and the center conductor of the port. The center conductor is preferably widened somewhat where it engages the knife edge and tapers smaller at 27, to the diameter of the center conductor 7 projecting outward from the port. This taper serves electrically as a transformer and is shaped in consideration of that perform-- ance. The center conductor 7 is held in place by dielectric plug 28 in the port flange 8, attached to the housing flange 30, all at port IV. The other ports and their center conductors are constructed substantially as port IV with center conductor 7.

The ground plate 14 at the center of the switch rotor 11 is slotted at each end to clear the widened ends 27 of the port center conductors 7 where the rotor is rotated from one positionto another. The slots 31 and 32 in the plate define two legs at each end of the plate which engage spring contacts such as 33 attached to the inside wall of the housing. This plate and contacts insure a common grounded wall adjacent each of the isolated conductive parts 15 and 16 of the switch. Thus, an rf wave is conducted from port II to port I (where the switch is positioned as shown in FIG. 3) by a coaxial transmission line section formed by part 16, housing 6 and plate 14.

The two positions of the transfer switch are indicated by FIGS. 6 and 7. Position A is represented in FIG. 6 where ports III and IV are electrically connected and ports I and II are electrically connected. In the B position shown in FIG. 7, ports IV and I are connected and ports II and III are connected. From the description given above, it may be clear that switching from position A to position B is accomplished by energizing solenoid A via the micro-switch actuated by the drive from solenoid B. Likewise, switching from position B to position A is accomplished by energizing solenoid B via a with the housing as they are inserted into corresponding holes in the top of the housing and insure that the rotor drive shaft spline 20 projecting below the plate rigidly connects to the switch rotor axel 13. The slight projection 37 from the bottom of plate 34 engages a matching recess 38 in the top of the switch housing and the plate is secured to the housing by bolts such as bolt 39.

The drive shaft spline 20-extends from the drive shaft 41 carried by bearing 42 axially located in the plate 31 and contained therein by captive washer 43. At the other end of the drive shaft is the idler gear 44 which 7 engages the A cam gear 45a and the B cam gear 45b which are carried on axels 46a and 46b, respectively, attached to the top of plate 34. Concentric with the gears 45a and 45b and located above these gears are the solenoids A and B, respectively, denoted 47a and 47b, respectively. Each solenoid is contained within a solenoid cover denoted 48a and 48b which attach to solenoid plate 49a and 49b by cover screws 50a and 50b and so contain the solenoids A and B, respectively. The cover plates 49a and 49b are spaced above the plate 34 by spacer posts 51a and 51b, respectively. Through an opening at the center of each cover plate extends the solenoid drive shaft, these are solenoid drive shafts 52a and 52b for the solenoids A and B, respectively. Cam A, denoted 53a is fixedly attached to the end of shaft 52a and Cam B, denoted 53b is fixedly attached to the end of shaft 52b. Each juts above the corresponding cam gear. The cams engage the gears by pins which are fixed to the cams and extend into slots in the gear discs. Pin 54a fixed to cam 53a extends into slot 55a in gear 45a. Likewise, 54b fixed to cam 53b extends into a slot 55b in the disc of gear 45b. Thus, a

. more fully in FIG. which is a cross section view of the structure taken as shown in FIG. 9 and twice the scale of FIGS. 8 and 9. Similarly, cam B, denoted 53b, plays against roller 61b carried on boss 62b extending from detent arm 63b also carried by the plate 31. When the detent arm which is spring loaded towards the axis of the associated solenoid is moved away from that axis by the action of the cam, the boss contacts two springs which actuate associated micro-switches mounted to the plate 31. The boss 62a moves against the springs 64a and 650 which actuate micro-switches 66a mounted to the plate 31 by a switch mounting bracket 67 0. Similarly, micro-switches 66b are actuated by movement of the roller 61b which plays against cam 53b, depending upon the rotational position of solenoid B- Extending from each boss of each detent arm in an axial direction with respect to the solenoid axis is a locking pin which engages a slot attached to the bottom of the cam gear to lock the gear when the position of the associated cam permits the roller to move towards the position closest to the solenoid axis, such as the position of roller 61a when cam A is at the position shown in FIG. 9. Here the locking pin 71a engages the slot 720 defined by a ridge 73a which may be an integral part of the disc of cam gear 45a. When thus engaged, the gear 45a is locked in position and so the transfer switch rotor 11 is locked in position. A similar pin 71b which is part of the detent 63b positioned by roller 61b engages a slot 72b in a ridge 73b at the bottom of cam gear 45b. Cam gear 45b is locked when the slot 72b aligns with pin 71b. In FIG. 9, the position of solenoid B is such that the associated switches 66b are closed and the gear is unlocked.

FIG. 10 shows details of one of the detents which locks a gear and other details of the associated cam gear, and pin drive. Since both solenoids and the drive and switches associated therewith are constructed substantially the same, details are illustrated for only one of the solenoids. FIG. 10 shows the drive from solenoid B and is taken as illustrated in FIG. 9 showing the position of the detent for solenoid B at the position shown in FIG. 9. The cam gear axel 46b includes for example, the axel 46b attached to the gear support plate 75b by axel screw 76b and carrying bearing 77b to which cam gear 45b is attached. A cavity 78b in plate 31 which is disposed radially with respect to the axel contains detent bearing 79b upon which slides the detent arm 63b. Within the arm is the detent pin spring 81b and detent pin 82b carried in an accommodating bore 83b. This pin is urged by the'spring against detent stop spacer 84b at one end of the'bearing. The end 85b of detent arm abuts spacer 86b at the other end of the bearing. The spacer 84b is retained by plate 87b. The locking pin detent associated with solenoid A is constructed identically and parts thereof are referred to by the same reference numbers but with the letter designation a rather than b.

FIG. 12 illustrates an electrical schematic from the block terminal 90 to the switches 66a and 66b which energize the solenoids 47a and 47b via rectifiers 91a and 91b. An input control switch 92 energizes either terminals A or B of the block terminal with l 10 volt ac power for energizing either solenoid A or solenoid B. Terminal C of the block terminal is a common or ground for this ac power. Terminal D, E, F, and G, H, I provide logic and interlock output signals derived from the switches 66a and 66b. Some of the uses of these interlock signals will be described herein below.

In operation commencing with the transfer switch rotor in the A position illustrated by FIGS. 2, 3, and 9, the drive from solenoid A to the switch rotor is locked and switch 66b is closed. This is the switch that control energization of solenoid A. This position is illustrated by FIG. 11f which shows a short vector A and a long vector B at angular positions representing the positions of the A and B solenoids, respectively. The positions of these vectors A and B also represent the positions of arcs extending from each of the vectors A and B and denoted 55a and 55b represent theslot 55a and 55b in gears 45a and 45b, respectively, shown in FIGS. 8 and 9 and which limit the relative position of each of the cams with respect to its associated drive gear. When neither solenoid is energized at the electrical condition illustrated in FIG. 12, the slots 55a and 55b are at the positions shown in FIGS. 8 and 9 and 11f. These slots limit the positions of the associated cams andsolenoids. For example, each solenoid has a spring return which rotates the solenoid in the opposite direction to the direction the solenoid rotates when it is electrically energized. Since solenoid A drives counterclockwise and solenoid B drives clockwise as viewed from the top, the

spring returns in these solenoids urge solenoid A clockwise and solenoid B counterclockwise. Hence, when the slots 55a and 55b in the gears are positioned as shown in FIG. 9 and illustrated schematically in FIG. 11f, and neither solenoid is energized, the solenoid cams will be at positions relative to their associated slots as represented in FIG. 11f.

' When the input control switch 92 is switched to the B terminal of the block terminal 90, solenoid A is energized and drives its cam 53a in the counterclockwise direction as represented by arrow 94 in FIG. 11f. The first 45 of the solenoid motion is used to retract the locking pin 71a. This is done as cam 53a rotates counterclockwise from the position shown in FIG. 9 and represented in FIG. llf to the position represented in FIG. 11g. The radial motion of the locking pin 71a closes micro-switches 66a, one of which controls energization cf solenoid B and so at this point all of switches 66a and 66b are closed. The second 45 of rotation of solenoid A rotates the transfer switch rotor 90 in the clockwise direction as viewed in FIG. 3. This occurs because the gear ratio from either of the gears 45a or 45b to the idler gear 44 is 2 to 1 and so 45 of rotation of the solenoid produces a 90 rotation of the transfer switch rotor. Furthermore, counterclockwise rotation of solenoid A produces a clockwise rotation of the switch rotor. At the end of the second 45 of rotation of solenoid A, the transfer switch will be in the B position and the slots 55a and b will be at the positions indicated by FIGS. 11h, i, and j. In FIG. 11h, vector A represents the completed drive position of solenoid A and vector B represents the position of solenoid B at the beginning of the drive and before that solenoid has been returned by its spring return in a counter-clockwise direction to the end of its travel as limited by slot 55b. FIG. lli shows the position of solenoid B urged by the spring return. The positions represented by FIGS. 11h and i actually occur simultaneously, because solenoid B follows solenoid A as solenoid A is driven from the position shown in FIG. 11g to the position in FIG. llh

: and so both solenoids arrive substantially simultaneously at the position shown in FIG. lli. At this position, solenoid B locks as the locking pin 71b is aligned radially with slot 72b in the bottom of gear 45b. As this locking occurs, urged by spring 81b, the solenoid switch 66b opens, deenergizing solenoid A which returns by spring return to the position shown in FIG. llj to complete the switching cycle. At the completion of this cycle, solenoid B is locked and the energizing switch 66b controlled by solenoid B is open. Also solenoid B urged by its spring return to the position shown 8 r in FIG. llj closes switch 66a which controls energization of solenoid B.

The next cycle of operation, switching from the B position to the A position is represented by the sequence illustrated in FIGS. 11;: to He. Here, solenoid B is energized and the control switch 92 is switched to terminal A of the terminal block causing solenoid B and its 'cam to rotate clockwise as viewed from above in the direction of arrow in FIG. lla. Thereafter, the switching cycle is carried out in the same fashion to arrive again at the A position illustrated by FIG. lle or 11f and shown in FIG. 9.

Each of the micro-switches 66a and 66b includes two switches. In 66a these are 6621' and 66a. The first of these as already described controls energization of solenoid B. The other produces a voltage signal at terminal E or terminal F which is referred to herein as a'logic signal. These logic signals may be used to control energization of transmitters which feed through the transfer switch in such a manner that the transmitter is turned on only when the switch is properly positioned to feed power from that transmitter to a load. This is one use of the logic signals. Clearly, other uses can be made depending upon the application and functioning of the transfer switch in the system in which it is employed.

The switch 66b, as already described, controls energization of solenoid A. The switch 66b ganged to this, produces an interlock signal at terminal H or I depending upon its position. The interlock signals may be used, for example, .to remove voltages from each of the solenoids once they have reached the end of their travel so that further voltage cannot be applied to either solenoid until the transfer switch is fully driven into the opposite position. This .makes accidental switching due to loss of ac power impossible.

The manual override enabled by the knobs 4 and 5 at the top of the drive mechanism enable manually rotating the switch during loss of ac power. Clearly, two knobs are provided, however, only one is necessary to operate the switch from its present position to the opposite position. The position of the knobs indicates the position of the switch and also which of the two knobs is to be rotated to actuated the switch.

It is preferred that a circuit breaker be included in the common path of the ac side of the energizing power for the solenoids, which is terminal C of the block terminal 90. This may be either a manual reset or a thermal automatic reset relay such as relay 96. With either type, the circuit breaker will open if a solenoid draws current for more than two or three seconds. The thermal automatic reset type of relay, 96, will reclose the circuit after approximately 10 seconds.

A particularly advantageous use of the coaxial trans fer switch is in a broadcast system including two transmitters and two loads. One transmitter, the primary transmitter, feeds rf power through the switch to a broadcast antenna while the other transmitter, the standby transmitter, feeds through the switch at a low power level into a dummy load. Upon demand, or upon the happening of a detectable event, such as a failure in the primary transmitter, the transfer switch is energized automatically by a controller on control switch 92 which positions switch 92 to the A or B terminal of terminal block 90. If, for example, the transfer switch is in the A position with the primary transmitter feeding through the switch to a broadcast antenna and the standby transmitter coupling through the switch to a dummy load, and a failure occurs in the primary transmitter, control switch 92 is automatically switched to terminal B of block 90. This energizes solenoid A and the sequence shown by FIGS. 11f to 11 j commences.

At the beginning of this sequence, micro-switches 66a are open (at the position shown in FIG. 12) and so logic terminal E of the terminal block 90 is energized with a dc signal level from terminal D and logic terminal F is not so energized. Thereafter, in the sequence represented by FIGS. llfto llj, switches 66a (referred to in these FIGS. as Sw a), close at the beginning of the second 45 of rotation of solenoid A (when rotation of the transfer switch rotor commences), and switches 66a open again at the end of the second 45 of rotation of solenoid A (when rotation of the transfer switch rotor is completed). This momentary closing and opening of switch 66a" produces a pulse at logic terminal F and a complementary pulse at logic terminal E that turns off both transmitters at the beginning of the pulse, then turns on the standby transmitter only at the end of the pulse. Thus, while the transfer switch rotor is moving from one position to the other, both transmitters are off and the standby transmitter does not come on with full rf power until switching is completed. This avoids rf arcing as the switch rotor blades disengage and engage the center conductors of the switch ports.

A broadcast system incorporating a coaxial transfer switch functioning as described above is represented by the diagram in FIG. 13. The primary and standby transmitters 101 and 102 feed rf power through the rotary transfer switch 100 to a broadcast antenna 103 and dummy load 104, respectively. The transfer switch is shown in FIG. 13 in the A position.

Faults detected in the primary and standby transmitters by detectors 105 and 106, respectively feed signals to the control switch controller 107 which positions control switch 92 at the A or B terminal of block 90. When a failure in the primary transmitter occurs and is detected by detector 105, controller 107 switches switch 92 from its center position (no ac energizing power), to terminal B and the sequence described above ensues. In that sequence, the dc pulses at logic terminals E and F are decoded by transmitter logic circuits 108 producing signals to the On-Off switches 109 and 110 which control power from source 111 to the primary and standby transmitters.

In this sequence, following detection of a failure or fault in the primary transmitter, the logic circuits turn off both transmitters during the interval that the rotor of the transfer switch 100 is moving from the A position to the B position (see FIGS. 6 and 7). Upon reaching the B position, the primary transmitter remains off and the standby is turned on.

Thereafter, should a fault or failure be detected in the standby transmitter, the reverse sequence occurs and both transmitters are turned off while the transfer switch rotor moves from the B position to the A position. Then transmitter 101 is turned on and transmitter 102 remains off.

The embodiment of the invention described herein and the uses of that embodiment represents the preferred structure and use. It is to be understood that this is illustrative of the structure and use and variations, modifications, and improvements may be made by those experienced in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. In a multi-port coaxial power switch having a rotor for interconnecting ports, means for actuating the rotor comprising,

a first electrical drive for driving the coaxial switch from a second position to a first position,

first drive means from the first electrical drive to the rotor,

said first drive means including a first cam and a first gear directly driving the rotor and first means interconnecting the first cam and first gear,

a second electrical drive for driving the coaxial switch rotor in the opposite direction from the first position to the second position,

second drive means from the second electrical drive to the rotor,

switching means for coupling electrical power from a source to the first and second electrical drives,

whereby the first and second electrical drives are energized at different first and second intervals to position the switch at the first and second positions, respectively.

2. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 further comprising,

means for locking the first drive means at the second position of the rotor, and

the first cam being driven by the first electrical drive to unlock the first drive means,

whereby the switch rotor locks at the second position and is unlocked when the first electrical drive is energized and following energization of the first electrical drive, the first cam moves and unlocks the first drive means before the first gear moves to position the rotor.

3. In a multi-port coaxial power switch, means for actuating the rotor as in claim 2 further comprising,

means for locking the second drive means at the first position ofthe rotor, and

second means driven by the second electrical drive for unlocking the second drive means,

whereby the switch rotor locks at the first position and is unlocked when the second electrical drive is energized.

4. In a multi-port coaxial power switch, means for actuating the rotor as in claim 2 wherein,

following energization of the first electrical drive, the first drive means is unlocked before driving the rotor to the first position.

5. In a multi-port coaxial power switch, means for actuating the rotor as in claim 3 wherein,

following energization of the second electrical drive, the second drive means is unlocked before driving the rotor to the second position.

6. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 wherein,

said switching means includes a first switch actuated by said first cam for coupling electric power from the source to the second electrical drive.

7. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 wherein,

said switching means includes a second switch actuated by said second drive means for coupling electric power from the source to the first electrical drive.

8. In a muIti-port coaxial poer switch, means for actuating the rotor as in claim 3 wherein,

the second drive means includes a second cam and second gear directly driving the rotor and second means interconnecting the second cam and second gear,

whereby, following energization of the second electrical drive, the second cam moves and unlocks the second drive means before the second gear moves to position the rotor.

9. in a multi-port coaxial power switch, means for actuating the rotor as in claim 1 and further including,

means for locking the first drive means at the second position of the rotor, and

first means driven by the first cam for unlocking the first drive means,

whereby the switch rotor locks at the second position and is unlocked when the first electrical drive is energized means for locking the second drive means at the first position of the rotor, and

second means driven by the second electrical drive for unlocking the second drive means,

whereby the switch rotor locks at the first position and is unlocked when the second electrical drive is energized,

said switching means includes a first switch actuated by said first cam for coupling electric power from the source to the second electrical drive, and

said switching means includes a second switch actuated by said second drive means for coupling electric power from the source of the first electrical drive,

whereby, following energization of the first electrical drive. the first cam moves and unlocks the first drive means before the first gear moves to position the rotor.

10. In a multi-port coaxial power switch having a rotor for interconnecting ports, means for actuating the rotor comprising,

a first electrical drive for driving the coaxial switch from a second position to a first position,

first drive means from the first electrical drive to the rotor,

said first drive means including a first pin driven along an are by the firstelectrical drive and first means including a first slot engaged by the first pin, and driven by the first pin for driving the rotor from the second position to the first position,

a second electrical drive for driving the coaxial switch rotor in the opposite direction from the first position to the second position,

second drive means from the second electrical drive to the rotor,

switching means for coupling electric power from a source to the first and second electrical drives,

whereby the first and second electrical drives are en I ergized at different first and second intervals to position the switch at the first and second positions,

respectively. 

1. In a multi-port coaxial power switch having a rotor for interconnecting ports, means for actuating the rotor comprising, a first electrical drive for driving the coaxial switch from a second position to a first position, first drive means from the first electrical drive to the rotor, said first drive means including a first cam and a first gear directly driving the rotor and first means inter-connecting the first cam and first gear, a second electrical drive for driving the coaxial switch rotor in the opposite direction from the first position to the second position, second drive means from the second electrical drive to the rotor, switching means for coupling electrical power from a source to the first and second electrical drives, whereby the first and second electrical drives are energized at different first and second intervals to position the switch at the first and second positions, respectively.
 2. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 further comprising, means for locking the first drive means at the second position of the rotor, and the first cam being driven by the first electrical drive to unlock the first drive means, whereby the switch rotor locks at the second position and is unlocked when the first electrical drive is energized and following energization of the first electrical drive, the first cam moves and unlocks the first drive means before the first gear moves to position the rotor.
 3. In a multi-port coaxial power switch, means for actuating the rotor as in claim 2 further comprising, means for locking the second drive means at the first position of the rotor, and second means driven by the second electrical drive for unlocking the second drive means, whereby the switch rotor locks at the first position and is unlocked when the second electrical drive is energized.
 4. In a multi-port coaxial power switch, means for actuating the rotor as in claim 2 wherein, following energization of the first electrical drive, the first drive means is unlocked before driving the rotor to the first position.
 5. In a multi-port coaxial power switch, means for actuating the rotor as in claim 3 wherein, following energization of the second electrical drive, the second drive means is unlocked before driving the rotor to the second position.
 6. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 wherein, said switching means includes a first switch actuated by said first cam for coupling electric power from the source to the second electrical drive.
 7. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 wherein, said switching means includes a second switch actuated by said second drive means for coupling electric power from the source to the first electrical drive.
 8. In a multi-port coaxial poer switch, means for actuating the rotor as in claim 3 wherein, the second drive means includes a second cam and second gear directly driving the rotor and second means interconnecting the second cam and second gear, whereby, following energization of the second electrical drive, the second cam moves and unlocks the second drive means before the second gear moves to position the rotor.
 9. In a multi-port coaxial power switch, means for actuating the rotor as in claim 1 and further including, means for locking the first drive means at the second position of the rotor, and first means driven by the first cam for unlocking the first drive means, whereby the switch rotor locks at the second position and is unlocked when the first electrical drive is energized means for locking the second drive means at the first position of the rotor, and second means driven by the second electrical drive for unlocking the second drive means, whereby the switch rotor locks at the first position and is unlocked when the second electrical drive is energized, said switching means includes a first switch actuated by said first cam for coupling electric power from the source to the second electrical drive, and said switching means includes a second switch actuated by said second drive means for coupling electric power from the source of the first electrical drive, whereby, following energization of the first electrical drive, the first cam moves and unlocks the first drive means before the first gear moves to position the rotor.
 10. In a multi-port coaxial power switch having a rotor for interconnecting ports, means for actuating the rotor comprising, a first electrical drive for driving the coaxial switch from a second position to a first position, first drive means from the first electrical drive to the rotor, said first drive means including a first pin driven along an arc by the first electrical drive and first means including a first slot engaged by the first pin, and driven by the first pin for driving the rotor from the second position to the first position, a second electrical drive for driving the coaxial switch rotor in the opposite direction from the first position to the second position, second drive means from the second electrical drive to the rotor, switching means for coupling electric power from a source to the first and second electrical drives, whereby the first and second electrical drives are energized at different first and second intervals to position the switch at the first and second positions, respectively. 